If TDA7294 Can work in 30V AC transformer - Page 2 - diyAudio
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Old 16th May 2012, 11:39 PM   #11
Minion is offline Minion  Canada
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Stuff like that happens when you only read the first 3 words of a datasheet .....
if you read further you would see that it is only +/-50v with "No signal" .....

It actually only has an operating range of a max of +/-40v though I have used them at +/-42v(tda7293) .....
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Old 17th May 2012, 05:42 AM   #12
guaxian is offline guaxian  China
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7294working fine in 42v DC for a year. thanks all!
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Old 17th May 2012, 03:39 PM   #13
masood is offline masood  India
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Quote:
Originally Posted by vedmitraa View Post
Hi everybody, This is Vedmitrasharma from City of Tajmahal . Can somebody guide me how to parrellel T D A 7294 I.C.s to get more current power to drive subwoofers as the have done with L M 3886 in Berringer moniter box with 3 I.C.s .regards everybody .waiting for reply
dear vedmitra namaskaar,
do you have got this 3 ic pcb and from where you got these ics.plz send me the pcb image of three ic's.thanks a lot
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Old 17th May 2012, 10:36 PM   #14
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Originally Posted by guaxian View Post
7294working fine in 42v DC for a year. thanks all!
Here's four attractive ways to get rid of some extra voltage:

1
You could try Fairchild Stealth as a bridge rectifier. This will give the slight voltage drop and good results.
or
2
Alternatively, you could use an ordinary bridge rectifier and make a CRC type power supply, whereby "R" = D-D-D//R. That is one fairchild stealth (~2v) or three series ordinary diodes limiting the voltage drop of one resistor to 0.7v*3, about 2.1v. The value of "R" will be quite high so as to allow the voltage drop. It looks just like sticking a 2v diode parallel to the R in a CRC.
or
3
For a more orthodox approach, you could use an ordinary bridge rectifier, like KBPC1610 or KBPC1010 with 1 of 4.7nF parallel with each diode, an RC parallel with transformer secondaries, one or several MOV's for transformer primary. . . and also construct an ordinary crc type power supply for a bit cleaner DC. Perhaps a lot of noise removal can drop the extra 2v.
or
4
Last, but not least, any time there's a chip amplifier and too much voltage, you have a wonderful opportunity to improve quality by using a regulator, such as documented here: Chip amp with a regulated power supply (PSU). (like most normal amplifiers, TDA7293/4 will differ from that gainclone example by needing additional 220uF or 330uF added for v+ and v- directly at the chip power pins).
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Old 17th May 2012, 10:37 PM   #15
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Quote:
Originally Posted by guaxian View Post
7294working fine in 42v DC for a year. thanks all!
Didn't realise the thread was this old

Stressing the manual says it is a 100V chip doesn't change the fact it is specced as being a +/-40V chip and running it at 42V increases the power it has to dissipate, and therefor decreases the power available for music reproduction.

But the chip should handle the voltage without problems imho. But at the expense of more useless powerdissipation and therefor possibly less poweroutput. And for this reason it would also be madness to feed it with 40V for a 4 ohm load...
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